Impact-induced vibrations result when using many types of equipment, including archery bows and related archery equipment. An oscillating system typically vibrates with respect to at least one resonant frequency (e.g., for each degree of freedom of the system). In addition, an oscillating system may also vibrate at harmonics of the resonant frequency (i.e., twice the resonance frequency, four times the resonance frequency, etc.). Of course, an oscillating system may also vibrate, to a lesser extent, at other frequencies as may be excited therein. The resonant frequency of a system may be generally proportional to a constant, commonly referred to as the spring constant or spring coefficient and to the mass of the system. An oscillating system may also have an internal damping factor associated therewith which dampens or diminishes, over time, the amplitude of the oscillations. However, among other reasons, because archery bows are preferentially light to make the archery bow easier to carry and shoot and relatively stiff, such internal dampening may be relatively minute or ineffective for dampening vibrations of a bow system.
Relative to archery systems, when an arrow is launched from an archery bow, the bow may be described as an oscillating system. For example, in anticipation of shooting an arrow at an intended target, an archer nocks an arrow on the bowstring and draws an archery bow. Drawing the bowstring stores potential energy in the bow limbs. When the bowstring is released, most of the stored potential energy is transferred to the arrow, causing the arrow to fly according to the magnitude and direction of the force imparted to the arrow. Generally, at least some portion of the potential energy is not transferred to the arrow, but instead absorbed by the bow. Ideally, if all of the stored energy were transferred to the arrow, or were otherwise dissipated or stored, the bow would not vibrate after release of the arrow. Due to the physics, mechanics, and dynamics of the bow and the arrow system configuration, such vibration may be difficult, if not impossible, to eliminate completely.
Accordingly, a recoil or kick, in combination with attendant vibration, may be felt by the archer. Such vibrations inevitably result in problems for the bow hunter or archer. Specifically, such vibrations give rise to undesirable noise, may influence accuracy in shooting, may cause physical discomfort to the archer's hand and arm, and may cause undesirable wear and tear on the archery bow and string.
Dampening devices have been used in many ways to reduce vibrations in archery bows. One conventional approach for lessening the effects of archery bow system vibration has been to use dampening devices in combination with stabilizers. Stabilizers with dampening material incorporated therein are mounted to the bow riser and are designed to reduce torque and absorb vibration generated upon release of an arrow. Mechanical dampers incorporated into stabilizers are also used to reduce bow vibrations.
In addition, dampening devices have been mounted to other areas of the bow, including the riser, the limbs, and the bowstring. In one type of conventional mechanical damper, a metal cylinder may be filled with oil and a piston in the cylinder is allowed to travel back and forth within the oil-filled cylinder to dampen vibrations. A third type of bow stabilizer is a rod and mass system. Rod and mass stabilizers include a system of movable weights to tune the stabilizer resonant frequency to that of the natural frequency of the system.
Accordingly, it would be advantageous to provide improved dampening apparatuses and structures for dampening vibrations of archery bows and archery accessories. Although the above-discussion references archery systems, the present invention may also relate to other systems that may experience vibration.